Recently, tampons have been utilized which contain superabsorbent materials. These materials are usually polymeric in nature and have a greater capacity for absorption of fluid per unit weight than the cotton or rayon fibers which have previously been traditionally used in tampons. The increase in fluid capacity and capillary suction pressure exhibited by the superabsorbent materials is such that only minor amounts, i.e. between 5 and 30 percent by weight are needed when used with conventional cotton or rayon fibers to provide vastly improved capacity and better absorptive efficiency per unit weight. These improved tampons may be worn for substantially longer time than tampons without superabsorbent.
One noticeable shortcoming of these higher capacity tampons not experienced with tampon products free of superabsorbents is the fact that withdrawal of the used tampon exhibits substantially greater frictional drag. Various attempts at reducing the frictional drag have taken the form of reducing the bulk of the tampon, providing a softer, lower density and less compressed tampon pledget, isolating the superabsorbent material in the tampon interior, tapering the withdrawal end of the tampon, using smoother wrapper material to reduce friction and a wrapper which retains part of the menstrual fluid at the surface to aid in withdrawal. Also, U.S. Pat. Nos. 2,340,311; 2,734,505; and 2,854,978 disclose utilizing surfactants as insertion aids for the traditional, non-superabsorbent-containing tampons. These surfactants may be utilized either for purposes of chemically reacting with the menstrual fluid or in conjunction with solid waxy lubricants. The surfactants disclosed in the above patents are either of the soap class, i.e. alkali metal salts of fatty acids, alcohols, sulphonated alcohols, etc.; quaternary ammonium salts; alkanol amines; or short chain polyhydric alcohols.
In U.S. Pat. No. 2,340,311 a coating is provided to aid in retention of the absorbent material in a compressed form as well as to facilitate tampon insertion. The coating includes a film forming substance to provide the binding effect which is strong enough to resist the expansive force of the compressed material and is water dispersible so that "it can readily dissolve in the body fluids, especially in the presence of surface tension depressant". The coating may also have a surface active agent used to depress the surface tension of the fluids and the surface active agents described include a quaternary ammonium salt and several other conventional surfactants such as polyhydric alcohols. Other polyhydric alcohols may be present as a plasticizer. Since this particular patent utilizes the primary insertion aid matrix as a binding material the disclosure states that it must be solid at room temperature and rapidly dispersible after contact with fluid.
U.S. Pat. No. 2,854,978 describes the utilization of a foamed material to provide a slippery surface for ease of insertion. These foams are designed to be of a water dispersible solid having a surface active agent. The foams are set forth as a solid separate component which is distinct from the tampon absorptive surface and is considered a separate element which does not interact with the absorptive part of the tampon.
U.S. Pat. No. 2,734,505 describes a tampon having a two component covering at its leading edge. One component is a water dispersible surface active agent and between the surface active agent and the tampon is a covering layer which blocks the passage of moisture to the tampon body.
Prior art lubricants can therefore be summarized in the following manner. First, there is a class of solid so-called "insertion aids" which may or may not contain surfactant. These solid generally wax-like insertion aids are designed to aid in the insertion of the tampon and either dissipate rapidly when subjected to exposure to menstrual fluid or interfere with the absorptive function of the tampon itself due to the barrier properties associated with the solid material. These particular approaches would provide disadvantages when used to inhibit super absorption suction pressure because either they would dissipate completely with the menstrual fluid being therefore unavailable at withdrawal or they would interfere with fluid uptake due to the nature of the covering itself.